The specific engine oil to use in your car is listed in the owner’s manual or can be found with resources. Some of the most recommended types of motor oil are 5w30 or 5w40. These are ideal for starting engines at low temperatures and effective at high engine temperatures, meaning they can be used in most conditions. Where are they different and which one should you use? We investigate these two types of oil, what they are good for and why car manufacturers say you should use one instead of the other.
What does 5W40 and 5W30 use?
For any grade of motor oil, the “w” stands for “winter”, according to the Society of Automotive Engineers (SAE) multigrading system. The number before the ‘w’ indicates the viscosity (or thickness) of the oil at low temperatures, and the number before the ‘w’ indicates the viscosity at higher temperatures (100 ° C for kinematic viscosity and 150 ° C for dynamic viscosity). Oil that is too thick will not flow properly through your engine, while oil that is too thin will not protect parts. The viscosity increases as the temperature decreases and decreases as the temperature increases. When choosing a type of engine oil, you have to balance performance and protection. An oil that is more viscous while your engine is running will better protect engine parts, but may be too thick to effectively wet engine performance. That is why it is important to consult your engine manufacturer about exactly which oil quality is suitable. Engines are built differently, so the wrong oil is probably not suitable for your model.
For 5w30 oil
- The kinematic viscosity is between 9.3-12.5 mm² / s
Dynamic viscosity is 2.9 mPas.
For 5w40 oil
- The kinematic viscosity is between 12.5-16.3 mm² / s
- Dynamic viscosity is 3.5 mPas.
In practice, this means that any oil is just as viscous at lower temperatures and remains viscous at -30 ° C, but 5w40 oil outperforms 5w30 oils at higher temperatures and is effective up to 50 ° C ambient temperatures, instead of 30 ° C ° C.
5w40 and 5w30 engine oils have a winter viscosity rating of five, which means that they are effective down to -30 ° C, and are more viscous at very low temperatures, compared to, for example, 10w40 oils. As a result, 5w40 oils are likely to be used in more powerful engines that have higher operating temperatures and loads than the norm – for example, those in local environments, which are often in traffic or driven at particularly high speeds. If your vehicle is not designed to drive in a powerful manner, or if you are driving at a more thoughtful, eco-friendly pace, 5w30 oils are a good choice. These are generally better for certain engine parts, such as oil pumps, can clean the engine better and have a longer time due to having a lower temperature range.
How about 5W40 or 10W40 engine oil?
The choice between 5w40 motor oil and an alternative like 10w40 depends on the winter temperature in your area. 5w40 is better for starting your engine at low temperatures as it flows in this environment. When the engine is running and warm, the differences are negligible; 5w40 and 10w40 both have a high viscosity and even protect well against engine wear. Always refer to your owner’s manual when choosing a motor oil. Learn how to check and change your engine oil, view our range or contact our experts for more information.